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At 5-year follow-up in a meta-analysis, bariatric surgery appeared to provide sustained effects on weight loss.

Sleeve gastrectomy appeared to be more effective in weight loss than adjustable gastric banding and comparable with gastric bypass.

Three commonly performed bariatric surgery procedures led to substantial and durable weight loss with a low mortality risk, concluded the authors of an expansive review and meta-analysis of both randomized clinical trials (RCTs) and observational studies.

Five years after surgery the 161,756 patients included in the analysis maintained 26% to 37% of the loss from baseline body mass index (BMI). Results from 37 randomized clinical trials (RCTs) showed a 30-day mortality of 0.08% and mortality beyond 30 days of 0.31%.

Complications remained fairly common (17% overall), and the reoperation rate was 7%.

Consistent with previous studies, gastric bypass resulted in the greatest weight loss, and adjustable gastric banding was associated with the lowest complication rate. The newer sleeve gastrectomy procedure seemed to offer the best combination of weight loss and safety, as reported online in JAMA Surgery.

"We observed higher mortality in observational studies than in RCTs, which could be attributed to longer follow-up time in observational studies or a higher chance that mortality recorded in observational studies was not associated with surgery," Su-Hsin Chang, PhD, of Washington University in St. Louis, and co-authors reported.

"We also found higher complication, reoperation, and comorbidity remission rates in RCTs. This could be explained by more detailed monitoring and reporting of outcomes in RCTs because of smaller sample sizes and shorter follow-up times. Despite these differences, the direction of the effects is the same in all aspects."

As the database for clinical outcomes in bariatric surgery has grown, several issues have emerged regarding generalizability. Early clinical trials provided data for specific procedures performed in different sets of patients. Some of the better known reviews did not include studies conducted after 2003, the authors noted in their introduction.

Recent meta-analyses focused on RCTs and excluded data from early publications. Moreover, advances in surgical technology and increased experience of surgeons are not adequately represented in previous reviews, the authors continued.

Chang and colleagues performed a systematic review and meta-analysis aimed at quantifying risks and benefits of specific bariatric procedures in adults. They defined risks as perioperative and postoperative mortality, complications, and reoperation rates. Benefits comprised weight loss and remission of obesity-related diseases.

The review encompassed studies reported from Jan. 1, 2003, to March 31, 2012.

The 164 articles included in the final analysis consisted of 62 publications from 2003 to 2007 and 102 from 2008 to 2012. A third of the studies (54) were conducted in North America, 72 in Europe, 13 in Asia, and 25 in other regions. A majority of the studies (92) had follow-up of at least 2 years.

The patients had a mean age of 44.6, preoperative mean BMI of 45.62, and preoperative mean weight of 274 pounds. Almost 80% were women.

Obesity-associated comorbidities included type 2 diabetes in 26%, hypertension in 47%, dyslipidemia in 27%, sleep apnea in 25%, and cardiovascular disease in 7%.

Observational studies reported higher mortality as compared with the RCTs (0.22% at 30 days, 0.35% >30 days). Also in the observational studies, adjustable gastric banding was associated with the lowest perioperative and postoperative mortality (0.07% and 0.21%), followed by sleeve gastrectomy (0.29% and 0.34%), and gastric bypass (0.38% and 0.72%).

Meta-analyses of complications comprised data from 64 studies. Complication rates were 17% in 16 RCTs and 10% in 48 observational studies. Similar rates were associated with each of the three surgical procedures evaluated.

Re-operation rates were similar in RCTs and observational studies (7% and 6%). The re-operation rate was lowest for gastric bypass (3%) in RCTs, whereas sleeve gastrectomy was associated with the lowest re-operation rate in observational studies (3%). Adjustable gastric banding had the highest re-operation rate in RCTs (12%) and observational studies (7%).

Change in BMI at 1 year was reported by 69 studies, and 11 studies had 5-year BMI data. BMI loss within 5 years of surgery ranged from 12 to 17 across observational studies. Two reports from the long-running Swedish Obese Subjects Study showed BMI loss of 6.5 at 10 years and 7.1 at 15 years.

The analysis of comorbidity outcomes comprised data from 53 studies. Remission of type 2 diabetes occurred in 92% of patients in RCTs and 86% of patients in observational studies. Hypertension remission rates were 75% in RCTs and 74% in observational studies.

The analysis of dyslipidemia remission included five RCTs, 20 observational studies, and almost 1,800 patients. Remission rates were 76% in the RCTs and 68% in the observational studies.

Sleep apnea remission was reported in five RCTs and 27 observational studies involving a total of 9,900 patients. The apnea remission rate was 96% for the RCTs and 90% for the observational studies. Of 27 patients with cardiovascular disease 58% met criteria for remission.

The study represents an important update of outcomes with different bariatric surgery procedures, said Vivek Prachand, MD, of the University of Chicago. The analysis relied on information published since 2003, whereas previous publications involved older studies.

The use of data from both RCTs and observational studies also distinguishes the analysis from prior reviews, most of which relied on RCTs.

The analysis shows that "bariatric surgery, overall, appears to be a very effective treatment for severe obesity, and it is a safe treatment in terms of mortality rate and complication rate," Prachand told MedPage Today.

"The fact of the matter is, there are several different operations that are being performed and there are differences in outcomes, differences in complications that need to be taken into account when recommending any particular procedure for any individual patient.

One caveat, he added: Chang and colleagues included data from the Swedish trial, which evaluated outcomes with bariatric procedures that are no longer used.

The study was supported by the National Cancer Institute, Foundation for Barnes-Jewish Hospital, and the American Cancer Society.

The authors disclosed no relevant relationships.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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